Specify the full path to the NEWLINE constant

middleman-core/features/helpers_select_tag.feature

@@ -0,0 +1,19 @@
+Feature: select_tag helper
+
+  Scenario: select_tag produces correct options
+    Given a fixture app "indexable-app"
+    And an empty file named "config.rb"
+    And a file named "source/select_tag.html.erb" with:
+    """
+    options as array: <%= select_tag :colors, options: ["red", "blue", "blorange"], include_blank: "Choose a color" %>
+    """
+    And the Server is running at "indexable-app"
+    When I go to "/select_tag.html"
+    Then I should see:
+    """
+    <select name="colors"><option value="">Choose a color</option>
+    <option value="red">red</option>
+    <option value="blue">blue</option>
+    <option value="blorange">blorange</option>
+    </select>
+    """

middleman-core/lib/middleman-more/core_extensions/default_helpers.rb

@@ -49,7 +49,7 @@ class Middleman::CoreExtensions::DefaultHelpers < ::Middleman::Extension
       output = ActiveSupport::SafeBuffer.new
       output.safe_concat "<#{name}#{attributes}>"
       if content.respond_to?(:each) && !content.is_a?(String)
-        content.each { |c| output.safe_concat c; output.safe_concat NEWLINE }
+        content.each { |c| output.safe_concat c; output.safe_concat ::Padrino::Helpers::TagHelpers::NEWLINE }
       else
         output.safe_concat "#{content}"
       end